Respiratory System Functions Quiz
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Questions and Answers

Which of the following is NOT a primary function of the lung?

  • Acting as a blood reservoir (correct)
  • Gas exchange
  • Converting angiotensin I to angiotensin II
  • Production of arachidonic acid metabolites

    • In which specific area of the respiratory system does gas exchange occur?

  • Trachea and bronchi
  • Bronchi and primary bronchioles
  • Respiratory bronchioles and alveoli (correct)
  • Terminal bronchioles and alveolar ducts

    • What is the shape and clustering arrangement of the alveoli within the respiratory system?

  • Spherical and evenly distributed
  • Irregular and dispersed
  • Polyhedral and clustered (correct)
  • Cylindrical and branched

    • What is the role of the conducting zone within the respiratory system?

    <p>Filtering, warming, and humidifying air.</p> Signup and view all the answers

    Which of the following is NOT a function of the alveolar macrophages?

    <p>Producing surfactant.</p> Signup and view all the answers

    Which of the following is a specific role of the lung in relation to angiotensin?

    <p>Converts angiotensin I to angiotensin II.</p> Signup and view all the answers

    Besides angiotensin, what other substance is metabolized by the lungs?

    <p>Bradykinin</p> Signup and view all the answers

    Which of the following is a key aspect in the properties of the lung concerning its natural behavior?

    <p>Its tendency to return to its resting volume after expansion</p> Signup and view all the answers

    Which of the following is NOT a primary function of the respiratory system?

    <p>Filtering unwanted materials directly for circulation.</p> Signup and view all the answers

    What is the primary mechanism for gas exchange within the respiratory system?

    <p>Passive diffusion down concentration gradients.</p> Signup and view all the answers

    Which process describes the movement of air into and out of the lungs?

    <p>Ventilation</p> Signup and view all the answers

    What is a key pre-processing function performed on inspired air by the respiratory system?

    <p>Warming and humidifying</p> Signup and view all the answers

    What role do cilia play in the respiratory system?

    <p>Moving mucus and trapped particles towards the throat</p> Signup and view all the answers

    External respiration directly involves:

    <p>The movement of air in and out of the lungs and gas exchange with blood</p> Signup and view all the answers

    What is the final destination of mucus that is mobilized by cilia in the respiratory system?

    <p>It is expectorated or swallowed.</p> Signup and view all the answers

    Which of the following statements BEST describes the process of internal respiration?

    <p>Gas exchange between blood and tissues and oxygen use by tissues</p> Signup and view all the answers

    What is a major consequence of emphysema on the respiratory system?

    <p>Destruction of alveolar tissue leading to fewer, larger alveoli</p> Signup and view all the answers

    Which mechanism is primarily responsible for airway obstruction during an asthma episode?

    <p>Bronchoconstriction due to inflammation</p> Signup and view all the answers

    What triggers the inflammatory response in asthma patients?

    <p>Inhalation of cold, dry air</p> Signup and view all the answers

    Which of the following statements about Chronic Obstructive Pulmonary Disease (COPD) is accurate?

    <p>It involves chronic inflammation leading to airway narrowing.</p> Signup and view all the answers

    What is the effect of cigarette smoking on the lungs related to emphysema?

    <p>It stimulates the release of inflammatory cytokines.</p> Signup and view all the answers

    What physiological change occurs in the bronchioles during emphysema?

    <p>Collapse of bronchioles during expiration</p> Signup and view all the answers

    Which condition is characterized by the accumulation of fibrous connective tissue in the lungs?

    <p>Pulmonary Fibrosis</p> Signup and view all the answers

    What measurement is often used to diagnose asthma?

    <p>Forced expiratory volume</p> Signup and view all the answers

    Which muscle primarily increases the vertical dimension of the chest cavity during inspiration?

    <p>Diaphragm</p> Signup and view all the answers

    What causes the rib cage to move upwards and outwards during inspiration?

    <p>Contraction of external intercostal muscles</p> Signup and view all the answers

    Which accessory muscle is responsible for elevating the first two ribs?

    <p>Scalene muscles</p> Signup and view all the answers

    What is the characteristic of expiration under normal resting conditions?

    <p>It is primarily passive</p> Signup and view all the answers

    During forced expiration, which muscle specifically assists in decreasing the volume of the thorax cavity?

    <p>Abdominal muscles</p> Signup and view all the answers

    Which change occurs in the alveolar pressure during inhalation?

    <p>Alveolar pressure decreases</p> Signup and view all the answers

    What role do internal intercostal muscles play during forced expiration?

    <p>They contract to depress the rib cage</p> Signup and view all the answers

    Which muscles are considered auxiliary during inspiration, particularly in respiratory distress?

    <p>Accessory muscles</p> Signup and view all the answers

    What happens to the internal pressure of the alveoli when the thoracic volume decreases during expiration?

    <p>Increases significantly</p> Signup and view all the answers

    Which of the following muscles is NOT used during quiet breathing?

    <p>Accessory muscles</p> Signup and view all the answers

    What is the primary role of the internal intercostal muscles during expiration?

    <p>Pull ribs downward and inward</p> Signup and view all the answers

    What does the work of breathing primarily overcome?

    <p>Elastic recoil of the lung</p> Signup and view all the answers

    Which of the following accurately describes tidal volume (TV)?

    <p>Amount of air expired or breathed in during quiet breathing</p> Signup and view all the answers

    How do bronchodilators affect work of breathing?

    <p>They reduce airway resistance</p> Signup and view all the answers

    What does the FEV/FVC ratio indicate?

    <p>The amount of air that can be exhaled in one second</p> Signup and view all the answers

    In what condition would you expect increased work of breathing and higher oxygen consumption?

    <p>Chronic severe asthma</p> Signup and view all the answers

    Which muscle primarily aids in forced expiration by pulling ribs towards the sternum?

    <p>Transversus thoracic muscle</p> Signup and view all the answers

    What is the typical range for work done during quiet breathing?

    <p>0.3 – 0.8 kgm/min</p> Signup and view all the answers

    Which of the following best describes vital capacity (VC)?

    <p>The sum of inspiratory reserve, tidal volume, and expiratory reserve</p> Signup and view all the answers

    What happens to respiratory muscle strength when severely stretched?

    <p>It reduces the strength of contraction</p> Signup and view all the answers

    What is the effect of pulmonary fibrosis on lung compliance?

    <p>Decreases compliance due to increased fibrous tissue</p> Signup and view all the answers

    Which variable directly affects the collapsing pressure in alveoli according to Laplace’s Law?

    <p>Surface tension and the radius of the alveolus</p> Signup and view all the answers

    Which of these factors is NOT a contributor to increased surface tension in the alveoli?

    <p>Presence of pulmonary surfactant</p> Signup and view all the answers

    How does aging affect lung compliance?

    <p>Decreases both elastic tissue and thoracic wall compliance</p> Signup and view all the answers

    What condition is characterized by a significant decrease in surfactant production leading to respiratory distress?

    <p>Acute respiratory distress syndrome</p> Signup and view all the answers

    What role does surfactant play in the alveoli?

    <p>Reduces surface tension to prevent lung collapse</p> Signup and view all the answers

    In which body position is lung compliance highest?

    <p>Prone position</p> Signup and view all the answers

    What effect does atelectasis have on lung compliance?

    <p>It decreases compliance due to reduced lung volume</p> Signup and view all the answers

    What is the relationship between intrapulmonary pressure and lung volume during ventilation?

    <p>Intrapulmonary pressure is inversely proportional to lung volume</p> Signup and view all the answers

    Which statement best describes the function of internal intercostal muscles during expiration?

    <p>They contract to assist in forced expiration by reducing thoracic cavity volume</p> Signup and view all the answers

    What primarily drives the absorption of fluid from the alveoli?

    <p>Osmosis driven by sodium active transport</p> Signup and view all the answers

    Which of the following conditions is associated with an increased lung compliance?

    <p>Pulmonary emphysema</p> Signup and view all the answers

    What effect does increased pulmonary venous pressure have on lung compliance?

    <p>It decreases compliance due to fluid presence in alveoli</p> Signup and view all the answers

    Study Notes

    Mechanics of Breathing

    • Breathing involves three phases: ventilation, gas exchange, and utilization of oxygen (cellular respiration).
    • External respiration involves air movement in and out of the lungs for gas exchange with blood.
    • Internal respiration involves gas exchange between blood and tissues, where oxygen is used by tissues.
    • Gas exchange is passive via diffusion.

    Learning Outcomes

    • Explain the general functions of the respiratory system.
    • Explain pulmonary compliance and factors affecting it.
    • Explain the role of surfactant and factors affecting it.
    • Explain the mechanics of breathing in relation to intrapleural and alveolar pressure.
    • Discuss the work of breathing.

    Structures of the Respiratory System

    • Warms and humidifies inspired air.
    • Mucus lining filters and cleans inspired air.
    • Mucus is moved by cilia for expectoration.
    • A conducting zone composed of the trachea, primary bronchi, bronchial tree, and terminal bronchioles.
    • Respiratory zone containing respiratory bronchioles, alveolar sacs, and alveoli. An estimated 500,000 respiratory bronchioles and 8 million alveoli exist in the lungs.

    Function of Lungs

    • Gas exchange (main function).
    • Gas exchange occurs in respiratory bronchioles and alveoli.
    • Alveoli, polyhedral in shape, cluster at ends of respiratory bronchioles like honeycomb units.
    • Other structures form the conducting zone.
    • Lung defense mechanism including filtration of foreign materials (bacteria, small particles), resisting infections, and maintaining mucosal integrity.
    • Blood reservoir regulating blood acid-base levels.
    • Speech production occurs as air is pushed out through the glottis, vibrating vocal cords.

    Pulmonary Compliance

    • Pulmonary compliance relates to the lung's and chest wall's distensibility (ease of expansion under pressure).
    • Compliant lungs expand easily.
    • Factors impacting compliance include lung size, body posture, and degree of lung inflation.
    • Atelectasis (lung collapse) results in decreased lung volume and increased pressure to inflate alveoli.
    • Pathological conditions such as pulmonary fibrosis (increase in fibrous tissues) and pulmonary edema (fluid in alveoli) decrease compliance, making lungs stiff.
    • Aging can also lead to decreased lung and chest-wall compliance, affecting the lungs' flexibility and ease of expansion.

    Elasticity

    • Elasticity is the tendency of the lung to return to its initial size after distension.
    • High elastin protein content contributes to this tendency.
    • Elastic tension increases during inspiration and decreases during expiration due to recoil.

    Surface Tension (ST)

    • ST and elasticity resist alveolar distension and promote collapse.
    • Lungs secrete and absorb fluid, normally leaving a thin fluid film on alveolar surfaces.
    • Fluid absorption occurs via osmosis, while fluid secretion involves active transport of chloride ions.
    • Surface tension is caused by water molecules' attraction to each other.
    • Surface tension causes pressure to increase within alveoli, which can potentially lead to alveolar collapse.
    • Surfactant reduces this surface tension.

    Surfactant

    • Surfactant secreted by Type II alveolar cells.
    • Lowers surface tension by reducing the attraction between water molecules and prevents alveolar collapse, primarily in newborns.
    • Without surfactant, the increased surface tension may impede airflow within smaller alveoli.
    • Lack of surfactant production in premature babies may lead to respiratory distress syndrome.
    • Related conditions affecting surfactant levels in adults can include heart surgery, blockage of the pulmonary artery, long-term exposure to 100% oxygen, and smoking.

    Physical Aspects of Ventilation

    • Ventilation results from pressure differences induced by changes in lung volumes.
    • Air moves from higher to lower pressures.
    • Compliance, elasticity, and surface tension of the lungs influence ease of ventilation.

    Mechanics of Breathing

    • At rest, intrapulmonary pressure equals atmospheric pressure.
    • During inspiration, intrapulmonary pressure lowers.
    • During expiration, intrapulmonary pressure increases.
    • Movement of air depends on pressure gradients.

    Boyle's Law

    • Pressure of a gas inversely proportional to volume.
    • Increases in lung volume result in lower intrapulmonary pressure.
    • Decreases in lung volume lead to higher intrapulmonary pressure.
    • Inspiration involves lung expansion and lower intrapulmonary pressure, drawing air into the lungs.
    • Expiration involves lung contraction, raising intrapulmonary pressure above atmospheric pressure.

    Intrapleural Pressure

    • Intrapleural pressure is subatmospheric.
    • Opposing forces of the lung and chest wall create negative pressure in the intrapleural space (approximately -4mmHg).
    • At rest, alveolar pressure equals atmospheric pressure (760mmHg).
    • Pneumothorax results when intrapleural pressure equals atmospheric pressure, causing lung collapse.

    Respiratory Muscles (Inspiration)

    • Diaphragm: most important inspiratory muscle increasing the vertical dimension of the chest cavity.
    • External intercostals: increase the lateral and anteroposterior dimension of the chest cavity.
    • Additional accessory muscles function during exercise or respiratory distress: scalene muscles, sternocleidomastoids, pectoralis minor, and serratus anterior muscles.

    Respiratory Muscles (Expiration)

    • Expiration is primarily passive.
    • Relaxation of inspiratory muscles and lung/chest wall elasticity allow for lung volume reduction.
    • Expiratory muscles are utilized during forced breathing or in situations of elevated airway resistance.

    Active Expiration

    • Internal intercostals: draw ribs downward, reducing the thoracic volume.
    • Transversus thoracic muscles: pull ribs toward the sternum, further reducing the thoracic volume.
    • Abdominal muscles (rectus abdominis, internal, and external obliques, transversus abdominis) increase intra-abdominal pressure.

    Work of Breathing

    • Respiratory muscles need energy to overcome the resistance of airflow, lung elasticity, and non-elastic tissues.
    • Work of breathing increases during strenuous exercise.

    Increased Work of Breathing

    • Conditions like inflated lungs (emphysema, asthma), low compliance (pulmonary edema, spinal deformity, obesity), high airway resistance (bronchospasm, mucus, bronchitis), and turbulent airflow (strenuous exercise) lead to increased work of breathing.

    Length-Tension Relationship

    • Respiratory muscle strength decreases when they are overly stretched.
    • Fatigue and inadequate ventilation are possible outcomes.
    • Increased airway resistance can be decreased by medications like bronchodilators, reducing the work of breathing.

    Pulmonary Function Tests

    • Spirometric tests are used to quantify lung volumes (tidal volume, inspiratory reserve volume, expiratory reserve volume, residual volume) and capacities (vital capacity, total lung capacity, inspiratory capacity, functional residual capacity).

    Vital Capacity (VC)

    • Vital capacity (VC) is the sum of inspiratory reserve volume, tidal volume, and expiratory reserve volume.

    Forced Expiratory Volume (FEV)

    • Forced expiratory volume (FEV): the volume of air forcefully exhaled in the first second of a forced expiration. Expressed as a ratio to the total forced vital capacity (FEV/FVC).
    • FEV1/FVC ratio is indicative of obstruction or restriction.

    Pulmonary Disorders (Restrictive)

    • Restrictive disorders are characterized by reduced vital capacity.
    • Examples include pulmonary fibrosis (scar tissue accumulation in the lungs leading to decreased elasticity and compliance), and other types of interstitial lung disease.
    • Symptoms can range from mild shortness of breath to difficulty breathing at rest.

    Pulmonary Disorders (Obstructive)

    • Obstructive disorders are characterized by difficulty in exhaling.
    • Examples include asthma (inflammation and bronchoconstriction of the airways), chronic bronchitis (inflammation of the bronchi leading to excessive mucus production), and emphysema (destruction of air sacs in the lungs making them lose their elasticity).
    • Symptoms can range from mild to difficulty breathing in severe cases.
    • COPD (Chronic Obstructive Pulmonary Disease) includes both emphysema and bronchitis.
    • Black lung disease (anthracosis) results from coal dust inhalation, leading to pulmonary fibrosis (reduced lung compliance).

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    Test your knowledge on the functions and structures of the respiratory system in this comprehensive quiz. Explore gas exchange, lung roles, and the workings of alveoli and conducting zones. Perfect for students of biology and health sciences.

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